Pharmacokinetics: Drug Metabolism and Excretion
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Questions and Answers

What is the primary focus of pharmacokinetics?

  • The mathematical description of the rate and extent of absorption, distribution, metabolism, and elimination of a drug (correct)
  • The pharmacological effect of a drug
  • The clinical effect of a drug
  • The binding of a drug to serum proteins

    • What is the primary route of elimination for most drugs?

  • Hepatic metabolism
  • Renal excretion (correct)
  • Biliary excretion
  • Enterohepatic recirculation

    • What is the term for the movement of a drug from the site of administration to the site of action?

  • Metabolism
  • Distribution
  • Elimination
  • Absorption (correct)

    • What is the term for the process by which a drug is broken down into its metabolites?

    <p>Biotransformation</p> Signup and view all the answers

    What is the term for the study of the movement of drugs within the body, including absorption, distribution, metabolism, and elimination?

    <p>Pharmacokinetics</p> Signup and view all the answers

    What is the characteristic of first-order elimination?

    <p>Rate of elimination is proportional to the concentration of the drug</p> Signup and view all the answers

    What happens to the blood profile if the dose is increased twofold, assuming small dose apparent first-order kinetics?

    <p>The blood profile is increased according to curve C</p> Signup and view all the answers

    What is the reason why F (bioavailability) is less than 1 for oral administration?

    <p>The drug is completely absorbed but some is metabolized in the liver</p> Signup and view all the answers

    Which route of administration bypasses the hepatic portal vein system?

    <p>Intravenous administration</p> Signup and view all the answers

    What is the term for the process by which a drug leaves the bloodstream and enters the tissues?

    <p>Distribution</p> Signup and view all the answers

    What does the volume of distribution (Vd) represent?

    <p>The volume of body water where the drug is distributed</p> Signup and view all the answers

    What is the unit of measurement for Cp(0)?

    <p>ug/ml</p> Signup and view all the answers

    What is the formula to calculate the volume of distribution (Vd)?

    <p>Vd = dose / Cp(0)</p> Signup and view all the answers

    What can be calculated from a graphical representation of drug distribution and elimination?

    <p>Both half-life and volume of distribution</p> Signup and view all the answers

    What is the unit of measurement for the volume of distribution (Vd)?

    <p>L</p> Signup and view all the answers

    What happens to the rate of elimination in a zero-order kinetics scenario?

    <p>It remains constant and is independent of drug concentration</p> Signup and view all the answers

    What is observed in a drug that exhibits mixed elimination kinetics?

    <p>A combination of zero-order and first-order kinetics</p> Signup and view all the answers

    What is the term for the time it takes for the plasma concentration of a drug to be reduced by half?

    <p>Half-life</p> Signup and view all the answers

    What happens to the elimination mechanism at high concentrations of a drug?

    <p>It becomes zero-order kinetics</p> Signup and view all the answers

    What is the shape of the curve obtained when a drug exhibits zero-order kinetics followed by first-order kinetics?

    <p>Curved with an initial slow phase followed by a rapid phase</p> Signup and view all the answers

    What can be calculated from a graphical representation of drug elimination?

    <p>Half-life</p> Signup and view all the answers

    What is the consequence of high plasma protein binding on a drug's volume of distribution?

    <p>It decreases the volume of distribution</p> Signup and view all the answers

    In pharmacokinetic modeling, what is the assumption regarding the rate of elimination in first-order kinetics?

    <p>The rate of elimination is proportional to the concentration of the drug</p> Signup and view all the answers

    What is the effect of lipophilicity on a drug's absorption and distribution?

    <p>Lipophilicity increases absorption and distribution</p> Signup and view all the answers

    What is the consequence of a drug's hydrophilicity on its bioavailability?

    <p>It decreases the bioavailability</p> Signup and view all the answers

    What is the primary reason behind Warfarin's low volume of distribution?

    <p>Reflects a high degree of plasma protein binding</p> Signup and view all the answers

    What is the half-life of the drug in the given graphical representation?

    <p>2 hours</p> Signup and view all the answers

    What is the characteristic of Chloroquine?

    <p>Highly-charged hydrophilic molecule</p> Signup and view all the answers

    What is the correct formula to calculate the volume of distribution (Vd) from a given plasma concentration (Cp)?

    <p>Vd = dose / Cp</p> Signup and view all the answers

    What is the volume of distribution (Vd) for a 70 kg man?

    <p>Unknown without additional information</p> Signup and view all the answers

    What is the time dependence of drug vs. plasma concentration for drugs that distribute rapidly?

    <p>Instantaneous</p> Signup and view all the answers

    What is the criteria for the FDA to consider two products bioequivalent?

    <p>Comparison of the test drug formulation to reference should be within 85% to 125%</p> Signup and view all the answers

    What is the pharmacokinetic parameter used to compare two drugs with identical active ingredients?

    <p>All of the above</p> Signup and view all the answers

    What is the absorption lag time (tlag) used to measure?

    <p>Delay between drug administration and the start of absorption</p> Signup and view all the answers

    Which of the following drugs distributes slowly and cannot be described by a single exponential constant?

    <p>Benzodiazepines</p> Signup and view all the answers

    What is the relationship between the half-life of a drug and its elimination rate constant?

    <p>Half-life is inversely proportional to the elimination rate constant</p> Signup and view all the answers

    What happens to the rate of elimination in a zero-order kinetics scenario?

    <p>The rate of elimination is constant and independent of drug concentration</p> Signup and view all the answers

    What is the shape of the curve obtained when a drug exhibits zero-order kinetics followed by first-order kinetics?

    <p>Biphasic with an initial slow elimination phase followed by a rapid elimination phase</p> Signup and view all the answers

    What happens to the elimination mechanism at high concentrations of a drug?

    <p>The elimination mechanism becomes saturated</p> Signup and view all the answers

    What is the characteristic of a drug that exhibits mixed elimination kinetics?

    <p>The drug exhibits zero-order kinetics at high concentrations and first-order kinetics at low concentrations</p> Signup and view all the answers

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